Rangers in Zimbabwe's Hwange National Park have discovered the carcasses of 26 elephants at two locations.

Officials said the animals were killed by cyanide poisoning.

Patrolling rangers discovered the carcasses on Tuesday, according to Bhejani Trust and the National Parks and Wildlife Management Authority. Bhejani Trust undertakes joint animal monitoring and welfare work with the parks agency

Parks spokeswoman Caroline Washaya Moyo said 14 tusks were recovered from the elephants and others were not recovered.

She said rangers found 16 of the elephants in an area known as Lupande and 10 others in Chakabvi.

Ms Washaya-Moyo said no arrests have been made and investigations are in progress. Rangers recovered one kilo of cyanide and are increasing patrols in the park. Cyanide is widely used in Zimbabwe's mining industry and is easy to obtain.

"The poachers were probably disturbed by rangers on patrol, which is why some of the tusks were recovered. Cyanide poisoning is becoming a huge problem here and we are struggling to contain it," Trevor Lane, founder of Bhejani Trust and a leading wildlife conservationist, said.

Last week, the parks agency reported that 14 elephants were poisoned by cyanide in three separate incidents.

In 2013, as many as 300 elephants died in Hwange park after poachers laced salt pans with cyanide.

On Monday, environment, Water and Climate Minister Oppah Muchinguri blamed a ban on Zimbabwean elephant sport hunting by the United States for increased poaching.

"All this poaching is because of American policies, they are banning sport hunting. An elephant would cost 120,000 US dollars (£78,000) in sport hunting but a tourist pays only 10 US dollars (£6) to view the same elephant," she said, adding money from sport hunting is crucial in conservation efforts.